Understanding the New Inclusion of RRFB Guidelines in the MUTCD’s 11th Edition

The 11th Edition of the Manual on Uniform Traffic Control Devices (MUTCD), published on December 19, 2023, marks a significant milestone in traffic control and pedestrian safety with the inclusion of Rectangular Rapid Flashing Beacons (RRFBs). This groundbreaking update underscores the commitment to enhancing pedestrian safety across uncontrolled crosswalks. 

RRFBs, known for their distinct flashing pattern, have proven effective in increasing driver awareness and yielding behavior, thereby reducing pedestrian-related crashes at uncontrolled marked crosswalks. Their formal recognition in the MUTCD paves the way for broader adoption and represents a major leap forward in improving safety and accessibility for pedestrians. 

RRFBs were first introduced as an experimental device in the MUTCD in 2008 and, with the exception of a few months in early 2018 where this status was rescinded due to a patent issue, have remained under an interim approval. With the long-awaited release of the 11th Edition of the MUTCD, the RRFB is now a formal device.

Discover below a brief overview of RRFBs as well as how these beacons have been integrated into the MUTCD’s 11th Edition traffic control guidelines, their design innovations, and operational standards, all of which contribute to a safer and more pedestrian-aware roadway environment.

The Essentials of RRFBs

Rectangular Rapid Flashing Beacons (RRFBs) have been proven to be an extremely effective device for improving safety of pedestrians and cyclists at uncontrolled marked crosswalks. Here is an overview of their design, function, and impact on safety:

Design and Concept

  • RRFBs consist of two yellow, rectangular-shaped LED indicators that flash rapidly when activated.
  • They are typically post mounted and positioned on both the left-hand and right-hand side of the crosswalk. For typical two-way roadway applications, the RRFB lightbars are usually mounted back-to-back on each pole.
  • Suitable for various settings such as crosswalks at uncontrolled intersections, mid-block crosswalks, trail crossings, crosswalks with median islands, and crosswalks at roundabouts.


  • Activated by pedestrians or cyclists at uncontrolled marked crosswalks.
  • Emit intense, rapid flashes, ensuring visibility under various lighting conditions, including bright daylight.


  • The vast majority of RRFBs are solar powered, which enables a cost effective installation as connections to the power grid for each pole are avoided.
  • RRFB devices are wirelessly connected to one another, so that when any push button at the crosswalk is pressed all RRFBs will start flashing immediately and stop flashing at the same time.

Safety Impact

  • Enhances driver awareness – The distinct flashing pattern stands out, alerting drivers to the presence of crossing pedestrians or cyclists.
  • Increases driver compliance – Research indicates RRFBs can increase motorist yielding rates by up to 98%.
  • Reduced Crash Rates – Extensive research has proven that RRFBs can reduce pedestrian crashes up to 47%.
  • Protects vulnerable road users – Especially effective for ensuring the safety of young, elderly, or disabled pedestrians and cyclists.

MUTCD 11: Chapter 4L Overview

The inclusion of Rectangular Rapid Flashing Beacons (RRFBs) in the Manual on Uniform Traffic Control Devices (MUTCD) 11th Edition, specifically in Chapter 4L, marks a significant advancement in road safety regulations. 

Firstly, this inclusion sets a national standard, ensuring uniformity and consistency in the implementation of RRFBs across the United States. Secondly, by formally integrating RRFBs into the MUTCD, it elevates these devices from the interim, experimental status to a recognized tool. This move not only standardizes their use but also encourages wider adoption and adherence to best practices in protecting vulnerable road users.

This chapter of the MUTCD provides comprehensive standards and guidelines for the installation, design, and operation of RRFBs. Here is a summary of its key points:

Application of RRFBs (Section 4L.01)

  • RRFBs are specifically for pedestrian-activated and/or bicyclist-activated use at marked crosswalks on uncontrolled approaches.
  • RRFBs can be used at crosswalks at roundabouts, and at intersections with two crosswalks on an uncontrolled approach.

Installation Standards

  • RRFBs are required to function as a supplement to the following specific signs: W11-2 (Pedestrian), S1-1 (School), or W11-15 (Trail) crossing warning signs.
  • RRFBs can be used on an approach in advance to the crosswalk, providing it is supplemental to, and not a replacement for, the RRFBs at the crosswalk itself. 

Design Specifications (Section 4L.02)

  • Each RRFB unit shall comprise of two rapidly-flashed, rectangular-shaped yellow indications that flash to the specific flash pattern detailed in this section.
  • The indications must be at least 5 inches wide and 2 inches high, aligned horizontally with a minimum space of 7 inches between them.
  • The placement of RRFB units should be in direct conjunction with the associated crossing warning signs, either on the same support or directly above/below the sign for post-mounted or overhead-mounted signs, respectively.

Operational Standards (Section 4L.03)

  • RRFBs must remain normally dark and only activate upon pedestrian actuation, ceasing operation after a predetermined time.
  • All associated RRFB units for a given crosswalk must commence and cease their rapid flashing simultaneously.
  • The flash rate and sequence are specifically defined to maximize visibility while avoiding frequencies that might induce seizures.

Additional Considerations

  • The light intensity of the RRFBs during daytime must meet or exceed the minimum specifications for SAE J595 Class 1 yellow peak luminous intensity.
  • To avoid excessive glare during nighttime automatic dimming  may be utilized.

Guidance for Enhanced Accessibility

  • The use of audible information devices with RRFBs is recommended to assist pedestrians with vision disabilities.
  • Small lights directed at pedestrians in the crosswalk may be integrated into the RRFB or pedestrian push button detector for operational confirmation.

This overview of MUTCD 11: Chapter 4L highlights the guidelines and standards set specifically for the implementation of RRFBs. These specifications ensure that RRFBs are used effectively and consistently across various locations, thereby enhancing the safety and visibility of pedestrian and cyclist crossings.

Why Choose Availed Technologies’ AV-400 RRFB?

Availed Technologies’ AV-400 Series RRFB meets and exceeds MUTCD standards and provides industry-leading installation simplicity. The AV-400 is purpose-built exclusively for the RRFB application, and provides numerous features to simplify the installation and reduce installation time and cost. Additionally, the AV-400’s capacity for over 300 daily activations surpasses the typical usage requirements of even busy crosswalks.

The ultra-efficient design of the AV-400 accomplishes this high operating capacity with a compact, lightweight solar engine that is very easy to handle and is small enough to be suitable for installation on standard sign posts.  The AV-400 solar engine and lightbars come with universal mounting brackets that readily mount to all pole types.

Availed Technologies’ AV-400 Series RRFBs are designed for efficiency and effectiveness:

  • Solar Engine and Battery – 20W high-efficiency monocrystalline solar panel with 45° tilt and 360° rotation, 12V 14-18 Ah AGM sealed lead acid battery.
  • Performance – Exceeds MUTCD light output requirements by up to five times, rated for over 300 activations per day.
  • Wireless Network – 2.4 GHz wireless mesh, 10 channels, 1000′ range, synchronized activation under 150ms.
  • Environmental Tolerance – Operates in -40 to 165° F, battery works in -40 to 140° F, compliant with NEMA TS 2 standards.
  • Installation – Quick and simple, with a pre-wired post-top solar engine assembly and a factory-installed universal mounting bracket.

If you are looking for more information on the use and installation of the AV-400 RRFB please visit our FAQ page.

Your MUTCD-Compliant RRFB Solution

The inclusion of RRFBs in the MUTCD’s Chapter 4L is a pivotal moment for road safety, acknowledging their importance in traffic management. This standardization is a major step in unifying safety practices nationwide.

By partnering with Availed Technologies, you’ll benefit from the AV-400 RRFB, an industry-leading product that adheres to MUTCD standards. Start your journey towards safer crosswalks by reaching out to us, and let us collaboratively enhance road safety.

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10 Do’s and Don’ts of RRFBs: Your Ultimate Guide

Below you will find the top 10 “do’s and don’ts” of using Rectangular Rapid Flashing Beacons, based on what we see working with municipalities every day on RRFB applications.

If you have a location where RRFB solutions are being considered please reach out! We would love to review your plans and ideas. Be sure to refer to the MUTCD 11th Edition, Chapter 4L for the official standards in the use of RRFBs.

Below is a comprehensive list of RRFB best practices:

1. Use RRFBs only at uncontrolled marked crosswalks

RRFBs are only to be used at crosswalks with pavement markings and signs where vehicles don’t have a stop control. The most common application is where the minor legs have stop signs and the major legs are through lanes. RRFBs can also be used at mid-block locations.

2. Install the RRFB on pedestrian, school, or trail signs, along with down arrow signs

RRFBs must be mounted below the W11-2 Pedestrian, S1-1 School, or W11-15 Trail crossing sign, and above the W16-7P down arrow sign. In Canada the RRFB lightbar is typically mounted above the RA-5 Pedestrian sign, and there is no down arrow.

3. Have RRFBs on both the left and right sides of the crosswalk

For a typical two-way roadway there is a pole on each side of the crosswalk, each with two RRFB lightbars mounted back-to-back. Placing RRFBs on both the left and right side frames the crosswalk and is therefore considered safe for pedestrians as it is more visible to drivers.

4. Signs must also be on both the left and right sides of the crosswalk

The MUTCD requires that pedestrian, school, or trail sign be installed on both the left and right sides of the crosswalk. The signs are typically mounted back-to-back like the lightbars are. This is different from using merely static signs at a crosswalk, where there is typically only a single sign facing oncoming traffic on the right side.

Incorrect Placement 🆇

This location is missing the signs that need to be on the left and right hand side along with the RRFB lightbars. In addition, the lightbar should be mounted between the School sign and the down-arrow sign.

Correct Placement ✅

This location has the correct RRFB lightbar and sign placement. Signs and lightbars are on both the left and right sides of the crosswalk for each approach.

5. Where there is a median, the left RRFB unit goes on the island

The set-up with a median island typically has single-sided light bars on the sides, and the median will have either:

a. one pole with dual back-to-back light bars, or
b. two poles with single sided light bars.

This provides the left and right ‘framing’ and, with the left unit in the middle of the roadway, it is very effective.

See the diagram on our resources page for a median island example of RRFB placement.

6. Where there are parallel crosswalks, a set of one-sided RRFBs should be placed on each crosswalk for maximum safety

Parallel crosswalks are important for serving pedestrians and cyclists who may be crossing a through road from both approaches. Single-sided RRFBs are used in each corner and when any button is pressed all four systems flash.

The diagram below is from page 737, Chapter 4L in the 11th Edition of the MUTCD from December 2023.

7. RRFBs can also go on overhead mast-arms – instead of just being post-mounted

If an overhead mast-arm is present over a pedestrian crosswalk, a minimum of one RRFB in each direction overhead is required. Typically, there are two RRFBs mounted overhead in each direction – and additional RRFBs can be post mounted as well.

8. Additional RRFBs can be mounted in advance of the units at the crosswalk

RRFBs can be installed in advance of the crosswalk with the pedestrian/school/trail sign along with the Ahead or Distance plaque. Advanced RRFBs are supplemental to and not a replacement for the RRFBs at the crosswalk.

9. Rapid flashing beacons must only flash when activated by a pedestrian

RRFBs are to remain in the off state until activated by a pedestrian, and once activated are to flash for a predetermined time (typically 20-30 seconds). The flash duration is to be based on the same procedures for the timing of pedestrian clearance times for pedestrian signals.

10. The RRFB indications on both sides of the crosswalk must all flash immediately, with no delay, and all turn off together

RRFBs must all start flashing immediately when the button is pressed, with no delay.  If the button is pressed again during the flash sequence the flash time resets.


We hope that you have learned some valuable information on RRFB implementation and best practices in this post. If you are looking to increase pedestrian safety in your city please feel free to reach out to us. Together we can walk through your idea and find the perfect options for your project.


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Crosswalk with two Availed RRFB poles on a sunny day. A castle-like house stands majestically in the background.

Specifying RRFBs – The Essentials

This article provides the essential Performance Requirements to include when specifying Rectangular Rapid Flashing Beacons (RRFBs).

Here at Availed Technologies, we work with municipalities and engineering firms across North America everyday who are in the process of specifying RRFBs. We focus on the following three points: Array to Load Ratio, Autonomy, and Shading.

Before we get into the performance requirements it should be noted that the operational requirements of an RRFB are important to specify and these are clearly defined in the MUTCD 11th Edition, Chapter 4L. One other point that is discussed at the end of this article is the option to use standard sign posts for RRFBs.

#1: RRFBs and Array to Load Ratio

The Array to Load Ratio is the power coming into the system divided by the power consumed by the system. It is the single most important metric to pay attention to when specifying Solar RRFBs. The ALR Ratio must be greater than 1:1, and a minimum of 1.2:1 is recommended. Regardless of the size of the solar panel or size of the battery, a system with an ALR of less than one means there is a power deficit and the system will run out of power eventually.

For Solar RRFBs, the ALR must be calculated using worst case conditions to ensure reliable year-round operation. This is typically in December when the solar energy available is at a minimum. The Solar insolation for a particular location is available through a comprehensive database from NREL that is based on historical information which accounts for prevailing weather conditions and latitude.

Factoring in the site-specific solar data, the daily power generated by the RRFB is determined by how the device converts the available solar energy into electrical energy that runs the system and is stored in the battery. This calculation is manufacturer-specific and varies significantly from one brand to another.

Power Consumed By RRFBs

The power consumed by the RRFB is also very manufacturer-specific and will vary even more from brand to brand than the power generation side of the equation. Power is consumed by the RRFB lightbars when they flash and also by the wireless connection between the systems which manages the activation of all systems at the crosswalk, so that when any one push button is pressed all the RRFBs start flashing immediately and stop flashing at the same time.

The wireless connection must always be ‘on’ and therefore this function is a significant portion of the power consumed. Advances in both LED and wireless technology have enabled dramatic improvements in power efficiency, the result of which is the ability to achieve a high ALR with a compact and lightweight system.

#2: RRFBs and Autonomy

The autonomy of an RRFB is defined as the number of days it can operate without any charging. It is a function of the daily power consumption and the battery capacity of the system. In an actual installation autonomy is hypothetical because the system will charge in the day even during cloudy conditions. Cold temperatures will decrease the battery capacity and this should be factored into an autonomy calculation.

Autonomy should never be the sole metric used in specifying a solar RRFB because it does not take into account the ‘power in’ of the system. Nevertheless, it is an important consideration as energy storage is essential for the system to function during nighttime and low light conditions. An autonomy of 5-10 days is recommended.

#3: RRFBs and Shading

Shading from trees and buildings is site specific and is often overlooked. At Availed Technologies, we can review the location with Google street view and we will incorporate this information when producing the solar performance report.

Key takeaways:

  • Always use ALR and Autonomy when specifying RRFBs
  • Use a solar performance report that factors in site specific shading to ensure system reliability
  • Never specify the solar panel size or battery capacity alone as these metrics do not factor in the power generation and power consumption of the system.

For further information on ALR, Autonomy, and RRFB efficiency see the article The Power of Solar RRFB Systems.

A final consideration when specifying RRFBs is the pole type. A positive benefit of an efficient system is that the product is compact and lightweight which makes it feasible to use standard sign posts. Using 2” Telespar square perforated tubing or standard 2” round sign posts will significantly reduce the installed cost of the system and will simplify the installation process. Standard sign posts can also be helpful for placement of RRFBs in locations where space is limited.

One feature worth mentioning regarding the Availed AV-400 RRFB is that it comes with a Universal mounting system that is compatible with all pole types, from the traditional 4 ½” diameter pedestal poles to 2” square and round posts, and everything in between.

Have any further questions about the essentials of RRFBs? Reach out to our team today!